Oil Pressure "LOW" ? 6.5L non-turbo

[rolling18]

Greetings!

I have driven my 2003 now about 3oo miles!!

Observations so far....
tire thumping about 50 Mph and up.. thumping consistent with speed but can go about 70 MPH (way too thumpy!) even after balancing
Tires:.. BFG Baja T/A made mid 2016..look like military type tread. stock bead-locked wheels (probably runflats going by weight )

Oil pressure "seems" low going by gauge...
during all my driving including floored up hills , off roading, highway / cty everything in between
I have NEVER seen a reading higher thAn 50 PSI.
warm Idle is about 20 PSI.....

I have tried a new Oil pressure sending unit,- no change
tested gauge- seems ok..
cleaned contacts of both items.. no change
Blowby observed- none.
no pressure felt even revving with my hand on fill neck..

Do I REALLY have "low oil pressure"??
or is the gauge needle not registering right?

if I really had that low of oil pressure how would I know? (symptoms?)

thanks for any assistance!

 

[dilvoy]

Greetings!

I have driven my 2003 now about 3oo miles!!

Observations so far....
tire thumping about 50 Mph and up.. thumping consistent with speed but can go about 70 MPH (way too thumpy!) even after balancing
Tires:.. BFG Baja T/A made mid 2016..look like military type tread. stock bead-locked wheels (probably runflats going by weight )

Oil pressure "seems" low going by gauge...
during all my driving including floored up hills , off roading, highway / cty everything in between
I have NEVER seen a reading higher thAn 50 PSI.
warm Idle is about 20 PSI.....

I have tried a new Oil pressure sending unit,- no change
tested gauge- seems ok..
cleaned contacts of both items.. no change
Blowby observed- none.
no pressure felt even revving with my hand on fill neck..

Do I REALLY have "low oil pressure"??
or is the gauge needle not registering right?

if I really had that low of oil pressure how would I know? (symptoms?)

thanks for any assistance!

IT has not blown up so it is enough oil pressure for your engine to run and live. These gauges are not accurate like those that are calibrated and have paperwork that follow them. They are just a guide of sorts. Even gauges in passenger cars are not exact from car to car. You could get a mechanical gauge for the oil and see what that shows. I would trust that more and then extrapolate those numbers to your Humvee gauge and be happy. A well broken in engine does not need that much oil pressure at idle to survive.

 

[Milcommoguy]

Greetings!

I have driven my 2003 now about 3oo miles!!

Observations so far....
tire thumping about 50 Mph and up.. thumping consistent with speed but can go about 70 MPH (way too thumpy!) even after balancing
Tires:.. BFG Baja T/A made mid 2016..look like military type tread. stock bead-locked wheels (probably runflats going by weight )

Oil pressure "seems" low going by gauge...
during all my driving including floored up hills , off roading, highway / cty everything in between
I have NEVER seen a reading higher thAn 50 PSI.
warm Idle is about 20 PSI.....

I have tried a new Oil pressure sending unit,- no change
tested gauge- seems ok..
cleaned contacts of both items.. no change
Blowby observed- none.
no pressure felt even revving with my hand on fill neck..

Do I REALLY have "low oil pressure"??
or is the gauge needle not registering right?

if I really had that low of oil pressure how would I know? (symptoms?)

thanks for any assistance!

Slippery subject... What do you think it should be?

These questions are answered in the 9-2320-280-10 Operator's Manual. Going by the limits, the engine oil pressure should be "more than 6PSI" once warmed up at idle and "more than 15 PSI" when under load, but it shouldn't really exceed 50 PSI.

Most would be happy with half that, CAMO

 

[Maxjeep1]

I have 60psi cold and 33 hot. That’s what the gauge says… it’s plenty!

 

[rolling18]

IT has not blown up so it is enough oil pressure for your engine to run and live. These gauges are not accurate like those that are calibrated and have paperwork that follow them. They are just a guide of sorts. Even gauges in passenger cars are not exact from car to car. You could get a mechanical gauge for the oil and see what that shows. I would trust that more and then extrapolate those numbers to your Humvee gauge and be happy. A well broken in engine does not need that much oil pressure at idle to survive.

ill have to look up how to run a mechanical gauge..
(I have 15,500 miles)

 

[rolling18]

Slippery subject... What do you think it should be?

These questions are answered in the 9-2320-280-10 Operator's Manual. Going by the limits, the engine oil pressure should be "more than 6PSI" once warmed up at idle and "more than 15 PSI" when under load, but it shouldn't really exceed 50 PSI.

Most would be happy with half that, CAMO

like the person below,... I read most people having 60- 80 psi!?

 

[rolling18]

I have 60psi cold and 33 hot. That’s what the gauge says… it’s plenty!

thats what I was thinking i should have too.. but Im going to add a different gauge somehow..

 

[Maxjeep1]

thats what I was thinking i should have too.. but Im going to add a different gauge somehow..

I think you are just fine and I believe that you are on the higher end of pressure! I wouldn’t waste my time or money chasing this. Many members would love to have the pressures that you are seeing. Drive the piss out of it!

 

[rolling18]

I think you are just fine and I believe that you are on the higher end of pressure! I wouldn’t waste my time or money chasing this. Many members would love to have the pressures that you are seeing. Drive the piss out of it!

i like this idea.. and makessense!

besides I THINK I NEED TIRES!! INSTEAD! HEH

 

[Maxjeep1]

I would worry about that low output generator you have. You need to upgrade to the 400 amp so you can run your house! I have one that I will trade you straight across! Hahaha

 

[rolling18]

I would worry about that low output generator you have. You need to upgrade to the 400 amp so you can run your house! I have one that I will trade you straight across! Hahaha

hmmm?? |
where did I mention a generator ,,,,,or anything about one?

 

[Maxjeep1]

hmmm?? |
where did I mention a generator ,,,,,or anything about one?

No that was me trying to help you get rid of the wimpy 200amp generator. I figured that if you wanted more oil pressure you would love more amps! Hahahaha I want to convert from my 400amp generator.

 

[rolling18]

No that was me trying to help you get rid of the wimpy 200amp generator. I figured that if you wanted more oil pressure you would love more amps! Hahahaha I want to convert from my 400amp generator.

Ahh gotcha,!
sory I wasnt in that frame of mind...

WHY woul dyou want to down grade from 400 amps?

 

[Maxjeep1]

Ahh gotcha,!
sory I wasnt in that frame of mind...

WHY woul dyou want to down grade from 400 amps?

Because it’s 30” long and blocks everything! Overkill for my needs

 

[Coug]

when I picked up my truck it showed 30psi cold, and 0psi hot idle.
Drove it about 1k miles that way.
Replaced both the gauge and the sender with new ones, this set reads 60ish oil pressure cold and 30ish hot idle. (until the sender started leaking through the electrical connector and started reading oil pressure levels above max and the needle was bouncing everywhere, and had to replace that sender. Replacement showed slightly higher oil pressures)

The way to do a mechanical gauge is just remove the electrical sender, and either install a T fitting to run both, or thread a mechanical gauge in (on a hose is a lot easier)
Some guys even do a mechanical gauge in the dash using a hydraulic type hose rather than the typical tiny plastic tube that comes with most gauge kits. A grease gun hose works great according to Hammer (on a different rig than the HMMWV though)

the gauge is there mostly as a guideline anyway, as there really isn't anything you can do about the pressure, and if it actually does get low, you've already toasted the bearings by the time you can pull over to do anything about it.

From reading a LOT of threads, the oil pump on these engines rarely has issues, so not really something to worry about. Either it's got pressure and you're good, or it doesn't and the engine is already toast.

I have one of these kits that does well for testing pressures:

Transmission/Engine Oil Pressure Kit | OTC Tools

www.otctools.com

 

[Mogman]

Your oil pressure is just fine, I do not understand why so many obsess about oil pressure, no body has 80 PSI unless they have a defective gauge.
BESIDES there is absolutely nothing you can do about the oil pressure anyway short of rebuilding or swapping engines and even then you will be right where you are now.
The 6.5L has piston cooling oil jets, this lowers the oil pressure as it is constantly "bleeding" off pressure through the jets.

 

[Sigi]

I don't see an issue. The old rule of thumb is 10psi for every 1000 rpm. In older two stroke Detroit Diesels the low oil pressure light would flicker at hot idle (5 psi). Never a problem as long as it rises with rpm.

 

[frauhansen]

My stays solid cold and warm at 30psi.... think the gauges in this rigs are morelike an indicater for high/low not for reading a reale

 

[mgFray]

2003 6.5L GEP - 20 psi idle, 50 psi max... When I first got it, it was reading 60psi all the time. I think both the gauge and original sender were bad.. replaced them as a pair and everything has been fine.

 

[juanprado]

The bfg baja tires are a civilian tread and far superior to goodyear in my opinion. Have you checked air pressure, tire balance?, shocks. Front end? Ujoints. Driveshaft?
Thumping is not normal and I suspect not a tire issue